1. Field of the Invention
The invention relates to an automatic charging device via a Universal Serial Bus (USB) and method of operating the same. In particular, the invention relates to a standard USB interface, which provides data transfer and has an additional function of charging. Therefore, the automatic charging device of the invention electrifies different chargeable means with different voltages simultaneously and has the advantages of easy carrying and prolonging the power lifetime of a battery.
2. Description of the Related Art
The USB is an interface provided for improving the communication between the external peripheral device and the host system. The USB provides the end user with the functions of Plug-and-Play (PnP) and hot plugging. The USB supports two kinds of data transfer rates of 1.5 Mbps and 12 Mbps, and has hardware standard. For example, in FIG. 1, an A-type plug connects a host computer of the upstream or a hub and a B-type plug connects an external peripheral device of the downstream via a USB. Because of the convenient property of the USB, the portable means, such as a mobile phone, a digital camera, a MP3 player, etc., uses the USB as the data transfer interface. However, the great power consumption of the portable means is one big headache.
The interface of an USB comprises: a. transferring data/w external power and b. transferring data/w internal power; however the USB interface doesn""t use as an interface with the functions of both charging and data transfer. Besides that, all of the portable means utilizing the USB as an interface can use the two transmitting-power pins (for example +5V and GND) in the A-type plug or the B-type plug described in FIG. 1 to transfer power, and such way of transferring power is named as a bus-power. According to one specification of a USB system, the USB can connect with 6 levels, which are up to 127 devices. However, the specification defines that one bus-power hub can not connect to another bus-power hub, and the purpose of the specification prevents the USB as an interface of the portable means connecting peripheral device from insufficient power to operate all the means. Because of the limitation of the specification, some feature of the described above USB is unable to full play. Consequently, if an USB interface can provide the functions of charge and data transfer simultaneously, the USB will solve the above problem.
An object of this invention is to solve the above-mentioned problems of the prior art by providing an automatic charging device via a USB and a method of operating the same. The invention provides a standard USB interface with the functions of charging and data transferring simultaneously, so the invention has the advantages of easy carrying and prolonging the power lifetime of a battery. The automatic charging device via an USB comprises: a battery charger electrifying the battery; an indicator showing the rate of progress; an USB interface connecting with the external peripheral device; and a charging controller utilizing a maximum charging current from a host system as a power source to electrify a battery in the battery charger via the USB interface, wherein the maximum charging current meets the maximum load current of the USB and the charging controller shows the charging current and the surplus current of the host system on a status window of the host system display. The method for electrifying peripheral device via a USB comprises the steps of: establishing an online USB between a peripheral device and a host system; obtaining a maximum current from the host system via the online USB by a charging controller; starting a battery charger and electrifying a battery by utilizing the maximum current as a power source, wherein a charging current from the power source is shown on an indicator; adjusting the charging current through the online USB to meet the maximum load current of the USB and showing both the charging current and a surplus current of the host system on a status window of a host system display; and terminating the charge as the battery is fully charged and decreasing the charging current to meet a minimum lord current of the USB otherwise repeating the step of adjusting the charging current through the USB.
In view of the above, the invention electrifies a peripheral device via the USB hardware standard. As the peripheral device connects the host system via the USB, the charging device automatically starts to charge a battery and the data is transferred from one end to another end through the USB. The invention doesn""t influence the data transmission time but prolong the power lifetime of a battery.